description LO/MO LIN GND ST/MN RO/MO+ MONO IN SHUTDOWN V DD BYPASS RIN DGQ PACKAGE (TOP VIEW)

Transcription

1 Ideal for Notebook Computers, PDAs, and Other Small Portable Audio Devices 2 W Into 4 Ω From 5-V Supply 0.6 W Into 4 Ω From 3-V Supply Stereo Headphone Drive Separate Inputs for the Mono (BTL) Signal, and Stereo (SE) Left/Right Signals Wide Power Supply Compatibility 2.5 V to 5.5 V Low Supply Current 4.2 ma Typical at 5 V 3.6 ma Typical at 3 V Shutdown Control... µa Typical Shutdown Pin Is TTL Compatible 40 C to 85 C Operating Temperature Range Space-Saving, Thermally-Enhanced MSOP Packaging MONO IN SHUTDOWN V DD BYPASS RIN DGQ PACKAGE (TOP VIEW) LO/MO LIN GND ST/MN RO/MO+ description The TPA023 is a 2-W mono bridge-tied-load (BTL) amplifier designed to drive speakers with as low as 4-Ω impedance. The amplifier can be reconfigured on the fly to drive two stereo single-ended (SE) signals into headphones. This makes the device ideal for use in small notebook computers, PDAs, personal digital audio players, anywhere a mono speaker and stereo headphones are required. From a 5-V supply, the TPA023 can deliver 2 W of power into a 4-Ω speaker. The gain of the input stage is set by the user-selected input resistor and a 50-kΩ internal feedback resistor (A V = R F /R I ). The power stage is internally configured with a gain of.25 V/V in SE mode, and 2.5 V/V in BTL mode. Thus, the overall gain of the amplifier is 62.5 kω/r I in SE mode and 25 kω/r I in BTL mode. The TPA023 is available in the 0-pin thermally-enhanced MSOP package (DGQ) and operates over an ambient temperature range of 40 C to 85 C. AVAILABLE OPTIONS PACKAGED DEVICES MSOP TA MSOP SYMBOLIZATION (DGQ) 40 C to 85 C TPA023DGQ AEH The DGQ package are available taped and reeled. To order a taped and reeled part, add the suffix R to the part number (e.g., TPA023DGQR). Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright 2002, Texas Instruments Incorporated POST OFFICE BOX DALLAS, TEXAS 75265

2 functional block diagram CB 4 BYPASS VDD 3 VDD GND 8 kω Mono Audio Input Ci RI 50 kω BYPASS 50 kω.25*r VDD 00 kω Right Audio Input Ci RI 5 MONO-IN RIN M U X + R + RO/MO+ 6 CC BYPASS BYPASS 00 kω 50 kω 50 kω Stereo/Mono Control ST/MN 7 50 kω.25*r Left Audio Input Ci RI 9 LIN M U X + R + LO/MO 0 CC BYPASS BYPASS kω From System Control 2 SHUTDOWN Shutdown and Depop Circuitry 2 POST OFFICE BOX DALLAS, TEXAS 75265

3 TERMINAL NAME NO. I/O Terminal Functions DESCRIPTION BYPASS 4 I BYPASS is the tap to the voltage divider for internal mid-supply bias. This terminal should be connected to a 0.-µF to -µf capacitor. GND 8 Ground terminal LIN 9 I Left-channel input terminal LO/MO 0 O Left-output in SE mode and mono negative output in BTL mode. MONO-IN I Mono input terminal RIN 5 I Right-channel input terminal RO/MO+ 6 O Right-output in SE mode and mono positive output in BTL mode SHUTDOWN 2 I SHUTDOWN places the entire device in shutdown mode when held low. TTL compatible input. ST/MN 7 I Selects between stereo and mono mode. When held high, the amplifier is in SE stereo mode, while held low, the amplifier is in BTL mono mode. VDD 3 I VDD is the supply voltage terminal. absolute maximum ratings over operating free-air temperature range (unless otherwise noted) Supply voltage, V DD V Input voltage range, V I V to V DD +0.3 V Continuous total power dissipation internally limited (see Dissipation Rating Table) Operating free-air temperature range, T A (see Table 3) C to 85 C Operating junction temperature range, T J C to 50 C Storage temperature range, T stg C to 50 C Lead temperature,6 mm (/6 inch) from case for 0 seconds C Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. DISSIPATION RATING TABLE PACKAGE TA 25 C DERATING FACTOR TA = 70 C TA = 85 C DGQ 2.4 W 7. mw/ C.37 W. W Please see the Texas Instruments document, PowerPAD Thermally Enhanced Package Application Report (SLMA002), for more information on the PowerPAD package. The thermal data was measured on a PCB layout based on the information in the section entitled Texas Instruments Recommended Board for PowerPAD on page 33 of that document. PowerPAD is a trademark of Texas Instruments POST OFFICE BOX DALLAS, TEXAS

4 recommended operating conditions ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ MIN ÁÁÁ MAX ÁÁÁ UNIT Supply voltage, VDD High-level input voltage, VIH ST/MN 2.5 VDD = 3 V 2.7 VDD = 5 V 4.5 V SHUTDOWN 2 VDD = 3 V.65 ST/MN Low-level input voltage, VIL VDD = 5 V 2.75 V SHUTDOWN 0.8 Operating free-air temperature, ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ TA ÁÁÁ 40 ÁÁÁ C 5.5 V 85 ÁÁÁ electrical characteristics at specified free-air temperature, V DD = 3 V, T A = 25 C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Output offset voltage (measured differentially)áááááááááááá RL = 4 Ω, ST/MN = 0 V, SHUTDOWN = 2 VÁÁÁÁÁÁÁ mv ÁÁÁÁ VOO ÁÁÁÁÁÁÁÁÁÁÁÁ 30 ÁÁÁ ÁÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁÁÁÁ VDD = 2.9 V to 3. V, ÁÁÁÁ BTL modeááááá 65 ÁÁÁÁÁ db SHUTDOWN, VDD = 3.3 V, VI = VDD ÁÁÁÁÁÁÁ ÁÁÁ I IH High-level input current A ST/MN, VDD = 3.3 V, VI = VDD ÁÁÁÁÁÁÁ ÁÁÁ µa SHUTDOWN, VDD = 3.3 V, VI = 0 V IIL Low-level input current ÁÁÁÁÁÁÁÁÁ µa A ST/MN, VDD = 3.3 V, VI = 0 V ÁÁÁÁÁ ÁÁÁÁÁ ÁÁÁÁ zi Input impedance ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ 50 kω IDD Supply current VDD = 2.5 V, SHUTDOWN = 2 V 3.6 ÁÁÁ 5.5 ÁÁÁ ma ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ IDD(SD) Supply current, shutdown mode SHUTDOWN = 0 V ÁÁÁ 0 ÁÁÁ µa ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ RF Feedback resistor VDD = 2.5 V, RL = 4 Ω, ST/MN =.375 V, ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ SHUTDOWN = 2 V ÁÁÁ 46 ÁÁÁ 50 ÁÁÁ 57 ÁÁÁ kω operating characteristics, V DD = 3 V, T A = 25 C, R L = 4 Ω, f = khz (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁTHD = %, BTL mode 660 PO Output power, see Note ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ mw THD = 0.%, SE mode, RL = 32 Ω 33 ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ THD + N Total harmonic distortion plus noise PO = 500 mw, f = 20 Hz to 20 khz 0.2% ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ BOM Maximum output power bandwidth Gain = 8 db, THD = 2% 20 ÁÁÁÁÁ khz ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ BTL mode 52 ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁ f = khz, ÁÁÁÁÁÁ CB = 0.47 µff ÁÁÁÁÁ SE mode ÁÁÁÁÁ 62 ÁÁÁÁÁ db ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ BTL mode ÁÁÁÁÁ 42ÁÁÁÁÁ Vn Noise output voltage CB = 0.47 ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ µf, f = 20 Hz to 20 ÁÁÁÁÁÁ khz µvrms ÁÁÁÁÁ SE mode ÁÁÁÁÁ 2ÁÁÁÁÁ NOTE : Output power is measured at the output terminals of the device at f = khz. 4 POST OFFICE BOX DALLAS, TEXAS 75265

5 electrical characteristics at specified free-air temperature, V DD = 5 V, T A = 25 C (unless otherwise noted) PARAMETER ÁÁÁÁÁÁÁÁÁÁÁ TEST CONDITIONS ÁÁÁÁÁÁÁ MIN TYP MAX UNIT Output offset voltage (measured differentially) RL = 4 Ω, ST/MN = 0 V, SHUTDOWN = 2 V mv ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ VOO 30 ÁÁÁ ÁÁÁÁ PSRR ÁÁÁÁÁÁÁÁÁÁÁÁ Power supply rejection ratio ÁÁÁÁÁÁÁÁ VDD = 4.9 V to 5. V, ÁÁÁÁ BTL modeááááá 62 ÁÁÁÁÁ db SHUTDOWN, VDD = 5.5 V, VI = VDDÁÁÁÁÁÁÁÁÁÁ IIH High-level input current A ST/MN, VDD = 5.5 V, VI = VDDÁÁÁÁÁÁÁÁÁÁ µa SHUTDOWN, VDD = 5.5 V, VI = 0 V ÁÁÁÁÁÁÁ ÁÁÁ I IL Low-level input current µa A ST/MN, VDD = 5.5 V, VI = 0 V ÁÁÁÁÁ ÁÁÁÁÁ zi Input impedance 50 kω ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ IDD Supply current SHUTDOWN = 2 V 4.2 ÁÁÁ 6.3 ÁÁÁ ma ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Supply current, shutdown mode SHUTDOWN = 0 V 0 ÁÁÁ µa IDD(SD) operating characteristics, V DD = 5 V, T A = 25 C, R L = 4 Ω PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ÁÁÁÁÁ THD = 0.3%, ÁÁÁÁÁÁ BTL mode W Output power, see Note ÁÁÁÁÁ THD = 0.%, ÁÁÁÁÁÁ SE mode, ÁÁÁÁÁ RL = 32 Ω ÁÁÁÁÁ mw Total harmonic distortion plus ÁÁÁÁÁ noise PO =.5 W, ÁÁÁÁÁÁ f = 20 Hz to 20 khzááááááááá ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Maximum output power bandwidth Gain = 6 db, THD = 2% khz ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁ 2 ÁÁÁÁÁ ÁÁÁÁ PO ÁÁÁÁÁÁÁÁÁ 90ÁÁÁÁÁ ÁÁÁÁ THD + N ÁÁÁÁÁÁÁÁÁ 0.2% ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ BOM 20 ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ BTL mode 52 ÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁ Supply ripple rejection ratio ÁÁÁÁÁ f = khz, ÁÁÁÁÁÁ CB = 0.47 µff ÁÁÁÁÁ SE mode ÁÁÁÁÁ 62 ÁÁÁÁÁ db ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ BTL mode ÁÁÁÁÁ 42 ÁÁÁÁÁ Vn Noise output voltage CB = 0.47 µf, f = 20 Hz to 20 khz V ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ SE mode µvrms ÁÁÁÁÁ 2ÁÁÁÁÁ NOTE : Output power is measured at the output terminals of the device at f = khz. TYPICAL CHARACTERISTICS Table of Graphs FIGURE vs Output power, 3, 5, 6, 8, 0 THD+N Total harmonic distortion plus noise vs Frequency 2, 4, 7, 9 Vn Output noise voltage vs Frequency Power supply rejection ratio vs Frequency 2, 3 POST OFFICE BOX DALLAS, TEXAS

6 TYPICAL CHARACTERISTICS THD+N Total Harmonic Distortion + Noise 0.0 TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER VDD =3 V Mono/BTL f = khz Gain = 8 db RL = 8 Ω RL = 4 Ω THD+N Total Harmonic Distortion + Noise TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY VDD = 3 V Mono/BTL RL = 8 Ω PO = 250 mw Gain = 20 db Gain = 8 db PO Output Power W Figure k 0k 20k f Frequency Hz Figure 2 THD+N Total Harmonic Distortion + Noise 0 0. TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER VDD = 3 V Mono/BTL RL = 8 Ω Gain = 8 db f = 20 khz f = 20 Hz f = khz THD+N Total Harmonic Distortion + Noise TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY VDD = 3 V Stereo/SE Gain =.9 db RL = 32 Ω PO = 25 mw RL = 0 kω VO = VRMS PO Output Power W Figure k 0k 20k f Frequency Hz Figure 4 6 POST OFFICE BOX DALLAS, TEXAS 75265

7 TYPICAL CHARACTERISTICS THD+N Total Harmonic Distortion + Noise 0 0. TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER VDD = 3 V Stereo/SE RL = 32 Ω Gain =.9 db f = 20 khz f = khz f = 20 Hz PO Output Power W Figure 5 THD+N Total Harmonic Distortion + Noise 0 0. TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER VDD = 5 V Mono/BTL f = khz Gain = 8 db RL = 8 Ω RL = 4 Ω PO Output Power W Figure 6 THD+N Total Harmonic Distortion + Noise TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY VDD = 5 V Mono/BTL RL = 8 Ω PO = W Gain = 20 db Gain = 8 db THD+N Total Harmonic Distortion + Noise 0 0. TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER VDD = 5 V Mono/BTL RL = 8 Ω Gain = 8 db f = 20 Hz f = 20 khz f = khz k 0k 20k f Frequency Hz Figure PO Output Power W Figure 8 POST OFFICE BOX DALLAS, TEXAS

8 TYPICAL CHARACTERISTICS THD+N Total Harmonic Distortion + Noise TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY VDD = 5 V Stereo/SE Gain =.9 db RL = 32 Ω PO = 75 mw k 0k 20k f Frequency Hz Figure 9 RL = 0 kω VO = VRMS THD+N Total Harmonic Distortion + Noise 0 0. TOTAL HARMONIC DISTORTION + NOISE vs OUTPUT POWER VDD = 5 V Stereo/SE RL = 32 Ω Gain =.9 db f = 20 khz f = khz f = 20 Hz PO Output Power W Figure 0 Output Noise Voltage µ V V n 00 Mono/BTL RL = 8 Ω Gain = 20 db Stereo/SE RL = 32 Ω Gain = 4 db OUTPUT NOISE VOLTAGE vs FREQUENCY Mono/BTL RL = 8 Ω Gain = 8 db Stereo/SE RL = 32 Ω Gain =.9 db PSRR Power Supply Rejection Ratio db POWER SUPPLY REJECTION RATIO vs FREQUENCY CB = 0.47 µf CB = µf CB = 0 µf Bypass = 2.5 V VDD = 5 V Mono/BTL Gain = 8 db k 0k 20k f Frequency Hz Figure k 0k 20k f Frequency Hz Figure 2 8 POST OFFICE BOX DALLAS, TEXAS 75265

9 PSRR Power Supply Rejection Ratio db TYPICAL CHARACTERISTICS POWER SUPPLY REJECTION RATIO vs FREQUENCY CB = 0.47 µf CB = µf Bypass = 2.5 V VDD = 5 V Stereo/SE Gain =.9 db k 0k 20k f Frequency Hz Figure 3 gain setting via input resistance APPLICATION INFORMATION The gain of the input stage is set by the user-selected input resistor and a 50-kΩ internal feedback resistor. However, the power stage is internally configured with a gain of.25 V/V in SE mode, and 2.5 V/V in BTL mode. Thus, the feedback resistor (R F ) is effectively 62.5 kω in SE mode and 25 kω in BTL mode. Therefore, the overall gain can be calculated using equations () and (2). A V 25 k R I (BTL) () A V 62.5 k R I (SE) (2) The 3 db frequency can be calculated using equation 3: ƒ 3 db 2 R I C i (3) If the filter must be more accurate, the value of the capacitor should be increased while the value of the resistor to ground should be decreased. In addition, the order of the filter could be increased. POST OFFICE BOX DALLAS, TEXAS

10 APPLICATION INFORMATION input capacitor, C i In the typical application an input capacitor, C i, is required to allow the amplifier to bias the input signal to the proper dc level for optimum operation. In this case, C i and the input resistance of the amplifier, R I, form a high-pass filter with the corner frequency determined in equation 4. 3 db f c(highpass) 2R I C i (4) The value of C i is important to consider as it directly affects the bass (low frequency) performance of the circuit. Consider the example where R I is 70 kω and the specification calls for a flat bass response down to 40 Hz. Equation 2 is reconfigured as equation 5. C i 2R f I c (5) In this example, C I is 5.6 nf so one would likely choose a value in the range of 5.6 nf to µf. A further consideration for this capacitor is the leakage path from the input source through the input network (C i ) and the feedback network to the load. This leakage current creates a dc offset voltage at the input to the amplifier that reduces useful headroom, especially in high gain applications. For this reason a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications as the dc level there is held at V DD /2, which is likely higher than the source dc level. Note that it is important to confirm the capacitor polarity in the application. power supply decoupling, C (S) The TPA023 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents oscillations for long lead lengths between the amplifier and the speaker. The optimum decoupling is achieved by using two capacitors of different types that target different types of noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic capacitor, typically 0. µf placed as close as possible to the device V DD lead, works best. For filtering lower-frequency noise signals, a larger aluminum electrolytic capacitor of 0 µf or greater placed near the audio power amplifier is recommended. midrail bypass capacitor, C (BYP) The midrail bypass capacitor, C (BYP), is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, C (BYP) determines the rate at which the amplifier starts up. The second function is to reduce noise produced by the power supply caused by coupling into the output drive signal. This noise is from the midrail generation circuit internal to the amplifier, which appears as degraded PSRR and THD+N. Bypass capacitor, C (BYP), values of 0.47 µf to µf ceramic or tantalum low-esr capacitors are recommended for the best THD and noise performance. fc 0 POST OFFICE BOX DALLAS, TEXAS 75265

11 APPLICATION INFORMATION output coupling capacitor, C (C) In the typical single-supply SE configuration, an output coupling capacitor (C (C) ) is required to block the dc bias at the output of the amplifier, thus preventing dc currents in the load. As with the input coupling capacitor, the output coupling capacitor and impedance of the load form a high-pass filter governed by equation 6. 3 db f c(high) 2R L C (C) (6) The main disadvantage, from a performance standpoint, is that the load impedances are typically small, which drives the low-frequency corner higher, degrading the bass response. Large values of C (C) are required to pass low frequencies into the load. Consider the example where a C (C) of 330 µf is chosen and loads vary from 3 Ω, 4 Ω, 8 Ω, 32 Ω, 0 kω, to 47 kω. Table summarizes the frequency response characteristics of each configuration. Table. Common Load Impedances vs Low Frequency Output Characteristics in SE Mode RL C(C) Lowest Frequency 3 Ω 330 µf 6 Hz 4 Ω 330 µf 20 Hz 8 Ω 330 µf 60 Hz 32 Ω 330 µf 5 Hz 0,000 Ω 330 µf 0.05 Hz 47,000 Ω 330 µf 0.0 Hz As Table indicates, most of the bass response is attenuated into a 4-Ω load, an 8-Ω load is adequate, headphone response is good, and drive into line level inputs (a home stereo for example) is exceptional. Furthermore, the total amount of ripple current that must flow through the capacitor must be considered when choosing the component. As shown in the application circuit, one coupling capacitor must be in series with the mono loudspeaker for proper operation of the stereo-mono switching circuit. For a 4-Ω load, this capacitor must be able to handle about 700 ma of ripple current for a continuous output power of 2 W. using low-esr capacitors Low-ESR capacitors are recommended throughout this applications section. A real (as opposed to ideal) capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance the more the real capacitor behaves like an ideal capacitor. fc POST OFFICE BOX DALLAS, TEXAS 75265

12 bridged-tied load versus single-ended mode APPLICATION INFORMATION Figure 4 shows a Class-AB audio power amplifier (APA) in a BTL configuration. The TPA023 BTL amplifier consists of two Class-AB amplifiers driving both ends of the load. There are several potential benefits to this differential drive configuration, but initially consider power to the load. The differential drive to the speaker means that as one side is slewing up, the other side is slewing down, and vice versa. This, in effect, doubles the voltage swing on the load as compared to a ground referenced load. Plugging 2 V O(PP) into the power equation, where voltage is squared, yields 4 the output power from the same supply rail and load impedance. See equation 7. V (RMS) Power V O(PP) V (RMS) R L (7) VDD VO(PP) VDD RL 2x VO(PP) VO(PP) Figure 4. Bridge-Tied Load Configuration In a typical computer sound channel operating at 5 V, bridging raises the power into an 8-Ω speaker from a singled-ended (SE, ground reference) limit of 250 mw to W. In sound power, that is a 6-dB improvement which is loudness that can be heard. In addition to increased power, there are frequency response concerns. Consider the single-supply SE configuration shown in Figure 5. A coupling capacitor is required to block the dc offset voltage from reaching the load. These capacitors can be quite large (approximately 33 µf to 000 µf) so they tend to be expensive and heavy. Also, they occupy valuable PCB area, and they limit low-frequency performance of the system. This frequency limiting effect is due to the high pass filter network created with the speaker impedance and the coupling capacitance and is calculated with equation 8. f c 2R L C (C) (8) 2 POST OFFICE BOX DALLAS, TEXAS 75265

13 APPLICATION INFORMATION bridged-tied load versus single-ended mode (continued) For example, a 68-µF capacitor with an 8-Ω speaker would attenuate low frequencies below 293 Hz. The BTL configuration cancels the dc offsets, which eliminates the need for the blocking capacitors. Low-frequency performance is then limited only by the input network and speaker response. Cost and PCB space are also minimized by eliminating the bulky coupling capacitor. VDD VO(PP) 3 db C(C) RL VO(PP) Figure 5. Single-Ended Configuration and Frequency Response Increasing power to the load does carry a penalty of increased internal power dissipation. The increased dissipation is understandable considering that the BTL configuration produces 4 the output power of the SE configuration. Internal dissipation versus output power is discussed further in the crest factor and thermal considerations section. single-ended operation In SE mode (see Figure 4 and Figure 5), the load is driven from the primary amplifier output for each channel (LO and RO, terminals 6 and 0) The amplifier switches to single-ended operation when the ST/MN terminal is held high. input MUX operation The input MUX allows two separate inputs to be applied to the amplifier. When the ST/MN terminal is held high, the headphone inputs (LIN and RIN) are active. When the ST/MN terminal is held low, the line BTL input (MONO-IN) is active. BTL amplifier efficiency Class-AB amplifiers are inefficient. The primary cause of inefficiencies is the voltage drop across the output stage transistors. There are two components of the internal voltage drop. One is the headroom or dc voltage drop that varies inversely to output power. The second component is due to the sinewave nature of the output. The total voltage drop can be calculated by subtracting the RMS value of the output voltage from V DD. The internal voltage drop multiplied by the RMS value of the supply current, I DD rms, determines the internal power dissipation of the amplifier. An easy-to-use equation to calculate efficiency starts out as being equal to the ratio of power from the power supply to the power delivered to the load. To accurately calculate the RMS and average values of power in the load and in the amplifier, the current and voltage waveform shapes must first be understood. See Figure 6. fc POST OFFICE BOX DALLAS, TEXAS

14 BTL amplifier efficiency (continued) APPLICATION INFORMATION VO IDD V(LRMS) IDD(avg) Figure 6. Voltage and Current Waveforms for BTL Amplifiers Although the voltages and currents for SE and BTL are sinusoidal in the load, currents from the supply are very different between SE and BTL configurations. In an SE application the current waveform is a half-wave rectified shape, whereas in BTL it is a full-wave rectified waveform. This means RMS conversion factors are different. Keep in mind that for most of the waveform both the push and pull transistors are not on at the same time, which supports the fact that each amplifier in the BTL device only draws current from the supply for half the waveform. The following equations are the basis for calculating amplifier efficiency. Efficiency of a BTL amplifier where P L V 2 LRMS R L P L P SUP (9), and V LRMS V P 2, therefore, P L V 2 P 2R L and P SUP V DD I DD avg and I DD avg therefore, 0 V P R L sin(t) dt V P R L [cos(t)] 0 2V P R L P SUP 2V DD V P R L substituting P L and P SUP into equation 9, V P 2 Efficiency of a BTL amplifier where V P 2P L R L 2R L 2V DD V P R L V P 4V DD Therefore, BTL 2P L R L 4V DD (0) P L = Power devilered to load P SUP = Power drawn from power supply V LRMS = RMS voltage on BTL load R L = Load resistance V P = Peak voltage on BTL load I DD avg = Average current drawn from the power supply V DD = Power supply voltage η BTL = Efficiency of a BTL amplifier 4 POST OFFICE BOX DALLAS, TEXAS 75265

15 APPLICATION INFORMATION BTL amplifier efficiency (continued) Table 2 employs equation 0 to calculate efficiencies for four different output power levels. Note that the efficiency of the amplifier is quite low for lower power levels and rises sharply as power to the load is increased resulting in a nearly flat internal power dissipation over the normal operating range. Note that the internal dissipation at full output power is less than in the half power range. Calculating the efficiency for a specific system is the key to proper power supply design. For a stereo -W audio system with 8-Ω loads and a 5-V supply, the maximum draw on the power supply is almost 3.25 W. Table 2. Efficiency Vs Output Power in 5-V 8-Ω BTL Systems Output Power (W) Efficiency (%) Peak Voltage (V) Internal Dissipation (W) High peak voltages cause the THD to increase. A final point to remember about Class-AB amplifiers (either SE or BTL) is how to manipulate the terms in the efficiency equation to utmost advantage when possible. Note that in equation 0, V DD is in the denominator. This indicates that as V DD goes down, efficiency goes up. crest factor and thermal considerations Class-AB power amplifiers dissipate a significant amount of heat in the package under normal operating conditions. A typical music CD requires 2 db to 5 db of dynamic range, or headroom above the average power output, to pass the loudest portions of the signal without distortion. In other words, music typically has a crest factor between 2 db and 5 db. When determining the optimal ambient operating temperature, the internal dissipated power at the average output power level must be used. The TPA023 data sheet shows that when the TPA023 is operating from a 5-V supply into a 4-Ω speaker 4-W peaks are available. Converting watts to db: P db 0Log P W P ref 0Log 4W W 6dB () Subtracting the headroom restriction to obtain the average listening level without distortion yields: 6 db 5 db = 9 db (5-dB crest factor) 6 db 2 db = 6 db (2-dB crest factor) 6 db 9 db = 3 db (9-dB crest factor) 6 db 6 db = 0 db (6-dB crest factor) 6 db 3 db = 3 db (3-dB crest factor) POST OFFICE BOX DALLAS, TEXAS

16 APPLICATION INFORMATION crest factor and thermal considerations (continued) Converting db back into watts: P W 0 PdB0 P ref 63 mw (8-dB crest factor) 25 mw (5-dB crest factor) 250 mw (2-dB crest factor) 500 mw (9-dB crest factor) 000 mw (6-dB crest factor) 2000 mw (3-dB crest factor) (2) This is valuable information to consider when attempting to estimate the heat dissipation requirements for the amplifier system. Comparing the absolute worst case, which is 2 W of continuous power output with a 3 db crest factor, against 2 db and 5 db applications drastically affects maximum ambient temperature ratings for the system. Table 3 shows maximum ambient temperatures and TPA023 internal power dissipation for various output-power levels. PEAK OUTPUT POWER (W) Table 3. TPA023 Power Rating, 5-V, 3-Ω, Mono AVERAGE OUTPUT POWER POWER DISSIPATION (W) MAXIMUM AMBIENT TEMPERATURE 4 2 W (3-dB crest factor).7 3 C mw (6-dB crest factor).6 6 C mw (9-dB crest factor).4 24 C mw (2-dB crest factor). 5 C 4 25 mw (5-dB crest factor) C 4 63 mw (8-dB crest factor) C PEAK OUTPUT POWER (W) Table 4. TPA023 Power Rating, 5-V, 8-Ω, Stereo AVERAGE OUTPUT POWER POWER DISSIPATION (W) MAXIMUM AMBIENT TEMPERATURE mw (3-dB crest factor) C mw (4-dB crest factor) C mw (7-dB crest factor) C mw (0-dB crest factor) C The maximum dissipated power, P Dmax, is reached at a much lower output power level for an 4-Ω load than for an 8-Ω load. As a result, this simple formula for calculating P Dmax may be used for a 4-Ω application: P Dmax 2V 2 DD 2 R L (3) However, in the case of an 8-Ω load, the P Dmax occurs at a point well above the normal operating power level. The amplifier may therefore be operated at a higher ambient temperature than required by the P Dmax formula for an 8-Ω load. The maximum ambient temperature depends on the heat sinking ability of the PCB system. The derating factor for the DGQ package is shown in the dissipation rating table. Converting this to Θ JA : Θ JA Derating Factor CW (4) 6 POST OFFICE BOX DALLAS, TEXAS 75265

17 APPLICATION INFORMATION crest factor and thermal considerations (continued) To calculate maximum ambient temperatures, first consider that the numbers from the dissipation graphs are per channel so the dissipated power needs to be doubled for two channel operation. Given Θ JA, the maximum allowable junction temperature, and the total internal dissipation, the maximum ambient temperature can be calculated with the following equation. The maximum recommended junction temperature for the TPA023 is 50 C. The internal dissipation figures are taken from the Power Dissipation vs Output Power graphs. T A Max T J Max Θ JA P D (0.8 2) 56 C (5-dB crest factor) NOTE: Internal dissipation of 0.8 W is estimated for a 2-W system with 5-dB crest factor per channel. Tables 3 and 4 show that for some applications no airflow is required to keep junction temperatures in the specified range. The TPA023 is designed with thermal protection that turns the device off when the junction temperature surpasses 50 C to prevent damage to the IC. Tables 3 and 4 were calculated for maximum listening volume without distortion. When the output level is reduced the numbers in the table change significantly. Also, using 8-Ω speakers dramatically increases the thermal performance by increasing amplifier efficiency. ST/MN (stereo/mono) operation The ability of the TPA023 to easily switch between mono BTL and stereo SE modes is one of its most important cost saving features. This feature eliminates the requirement for an additional headphone amplifier in applications where an internal speaker is driven in BTL mode but external stereo headphone or speakers must be accommodated. When ST/MN is held high, the input mux selects the RIN and LIN inputs and the output is in stereo SE mode. When ST/MN is held low, the input mux selects the mono-in input and the output is in mono BTL mode. Control of the ST/MN input can be from a logic-level CMOS source or, more typically, from a switch-controlled resistor divider network as shown in Figure 7. (5) POST OFFICE BOX DALLAS, TEXAS

18 ST/MN (stereo/mono) operation (continued) APPLICATION INFORMATION CB 4 BYPASS VDD 3 VDD GND 8 kω Mono Audio Input Ci RI 50 kω BYPASS 50 kω.25*r VDD 00 kω Right Audio Input Ci RI 5 MONO-IN RIN M U X + R + RO/MO+ 6 CC BYPASS BYPASS 00 kω 50 kω 50 kω Stereo/Mono Control ST/MN 7 50 kω.25*r Left Audio Input Ci RI 9 LIN M U X + R + LO/MO 0 CC BYPASS BYPASS kω From System Control 2 SHUTDOWN Shutdown and Depop Circuitry Figure 7. TPA023 Resistor Divider Network Circuit Using a readily available /8-in. (3,5 mm) stereo headphone jack, the control switch is closed when no plug is inserted. When closed, the 00-kΩ/-kΩ divider pulls the ST/MN input low. When a plug is inserted, the -kω resistor is disconnected and the ST/MN input is pulled high. The mono speaker is also physically disconnected from the RO/MO+ output so that no sound is heard from the speaker while the headphones are inserted. 8 POST OFFICE BOX DALLAS, TEXAS 75265

19 PACKAGE OPTION ADDENDUM 0-Jun-204 PACKAGING INFORMATION Orderable Device Status () Package Type Package Drawing TPA023DGQ ACTIVE MSOP- PowerPAD Pins Package Qty Eco Plan (2) DGQ 0 80 Green (RoHS & no Sb/Br) Lead/Ball Finish MSL Peak Temp Op Temp ( C) (6) (3) CU NIPDAU Level--260C-UNLIM -40 to 85 AEH Device Marking (4/5) Samples TPA023DGQR ACTIVE MSOP- PowerPAD DGQ Green (RoHS & no Sb/Br) CU NIPDAU Level--260C-UNLIM -40 to 85 AEH TPA023DGQRG4 ACTIVE MSOP- PowerPAD DGQ Green (RoHS & no Sb/Br) CU NIPDAU Level--260C-UNLIM -40 to 85 AEH () The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either ) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and Addendum-Page

20 PACKAGE OPTION ADDENDUM 0-Jun-204 continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2

21 PACKAGE MATERIALS INFORMATION 3-Aug-207 TAPE AND REEL INFORMATION *All dimensions are nominal Device TPA023DGQR Package Type MSOP- Power PAD Package Drawing Pins SPQ Reel Diameter (mm) Reel Width W (mm) A0 (mm) B0 (mm) K0 (mm) P (mm) W (mm) Pin Quadrant DGQ Q Pack Materials-Page

22 PACKAGE MATERIALS INFORMATION 3-Aug-207 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPA023DGQR MSOP-PowerPAD DGQ Pack Materials-Page 2

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